[cheetaprowlerDH]

different things work for different riders... its paid off for me. ride and understand all aspects of it...
all these pros we see today started out on muuuch lesser equipment than we have right now didnt they? look how much that progression has helped them... starting out at the peak doesnt get one any higher... and its much more boring:biggrin: i've always had a thing for taking the hard road, but theres a method to my madness and it is to gain an understanding of every little thing in order to become better off in the future... since i was 6 years old i have been like this and i think the knowledge i have gained and the way i apply it to all aspects my life is perfect... i beleive that it will only benefit me, so thats why i do it.

but sh!t, enough about me, this thread is about a fork:biggrin:

theres no way i would ever throw my 888 away, that wasnt my plan in the first place.
i cant ride my bike as is or i will ruin my fork even more and most likely get hurt myself... all the oil will drain within the first few compressions and something evil will probably happen to the damper rod that is in there... nothing in the lower half of the fork is tightened or tightenable...
i beleive need totally new internals for the left leg, but first i need to find a way to get the ones that are presently in there out...

 

[Jm_]

You should get a shiver SC. You haven't lived (and almost died many times) until you've tried to control a shiver SC through a rock garden. Oh so plush, and oh so scary. If you can go fast with that you will be unstoppable.

 

[blackspire]

other than being "cool looking" why do you want an inverted?
I've owned a Shiver and a Stratos S8. Both were plush, but really suffered in tracking.
Personally I wouldn't even consider one unless its paired to an oversized hub, like the Foes forks (but the SPV internals are crap!)

Get your 888 fixed by someone who knows whats up and you'll be stoked. Take it to Drake (I.S.O.) and he'll sort you out.

The reason for an upside down fork is that you have less unsprung weight. So in theory, if you would have had the same damping system in your Shiver or Stratos as in your 888 your wheel should track better, given that you use a wheel with the same weight (or more correct mass).

 

[Defenestrated]

Wheels don't track well when they are flexing all over.

 

[blackspire]

Wheels don't track well when they are flexing all over.

Wheels that flex too much is obviously a design flaw. Despite this the reason for inverted forks is to reduce the unsprung weight. It's a balance act between managing to do a fork that is stiff enough for the rider and lighter at the lower parts (the unsprung parts). If the wheels themselves are flexing not much can be done except trying another wheel, any flex in the fork can off course be fixed by the fork manufacturer. It obviously works for many motorbikes so it's likely that either the bicycle industry does not have the money to develop a inverted fork which works or there is not enough incentive to do so. So far the only upside down fork I've tried was a Avalanche I liked the feel of that. But they are abit heavy.

 

[Jm_]

The reason for an upside down fork is that you have less unsprung weight. So in theory, if you would have had the same damping system in your Shiver or Stratos as in your 888 your wheel should track better, given that you use a wheel with the same weight (or more correct mass).

Absolutely not. The reason for the inverted fork is bushing overlap, and as you extend the travel with a right side up fork you have to start doing things like making extended lowers at the dropouts and excessive axle to crown heights for the travel. This is what happened with moto forks, and out of necesity they switched to inverted designs to retain the proper amount of bushing overlap.

The unsprung weight thing is BS IMO. Sure it's there, but the lower stanchions and dropouts aren't weightless, and aluminum or mg casted lowers are very light, 3/4 of a pound for the old 35mm 66 series, and when you add up all of the unsprung weight (rim, rim strip, tire, tube, spikes, hub, axle, brake, disc rotor, etc) you're going to have less than a 10% change.

 

[Jm_]

It obviously works for many motorbikes

An overriding factor with motor bikes is that the fork has to be able to survive huge doubles, and occasionally casing some of those doubles. The one thing that an inverted fork does better is it maintains better fore-aft stiffness and strength due to the size of the uppers and the crowns/clamps. This isn't really a very valid idea for mtb though because you can offset this just by increasing the size of the stancions as fox has with the fox 40, but there is a limit due to bushing overlap of course. One other issue is that moto forks do not have brake arches, whether they are inverted or not, so it doesn't really make any sense to compare them due to the lack of this feature, which makes all the difference in the world for our right-side-up mtb forks.

There are reasons it works for motos, those reasons have nothing/little to do with mtb.

 

[blackspire]

Absolutely not. The reason for the inverted fork is bushing overlap, and as you extend the travel with a right side up fork you have to start doing things like making extended lowers at the dropouts and excessive axle to crown heights for the travel. This is what happened with moto forks, and out of necesity they switched to inverted designs to retain the proper amount of bushing overlap.

The unsprung weight thing is BS IMO. Sure it's there, but the lower stanchions and dropouts aren't weightless, and aluminum or mg casted lowers are very light, 3/4 of a pound for the old 35mm 66 series, and when you add up all of the unsprung weight (rim, rim strip, tire, tube, spikes, hub, axle, brake, disc rotor, etc) you're going to have less than a 10% change.

I don't understand what you mean by bushing overlap (english is not my native language). Care to explain further?

Using inverted forks are not only for motocross, they are used widely in other types of motorcycle racing (just look at any moto gp bike).

I also think you are wrong about the unsprung weight as unsprung weight is important when considering vehicle dynamics. Reducing unsprung weight in a vehicle not only affects the traction, it also affects braking in a positive way.

What do you mean by brake arches?

 

[Kanye West]

An ATA cartridge is not terribly expensive. Just call Marzocchi.

 

[Jm_]

I don't understand what you mean by bushing overlap (english is not my native language). Care to explain further?

Using inverted forks are not only for motocross, they are used widely in other types of motorcycle racing (just look at any moto gp bike).

I also think you are wrong about the unsprung weight as unsprung weight is important when considering vehicle dynamics. Reducing unsprung weight in a vehicle not only affects the traction, it also affects braking in a positive way.

What do you mean by brake arches?

Bushing overlap is the amount of stanchion that is "in" the fork bushing when it is resting and not being compressed. For the longest time marzochi tried to keep about 4" of overlap with all of their forks, I'm talking mostly about their single crown forks, but they did that with some of the double crowns as well.

So if you have an 8" non-inverted fork, the space between the upper and lower crowns is mostly hollow, maybe containing a spring, but usually just contains a spacer that extends down to where the spring starts. In other words this area serves a structural purpose for the dual-crown setup, but other than that it's not serving any other purpose. The bushing overlap is obviously within the lowers, and due to a finite amount of space, it can't be very large.

If you have an 8" inverted fork (like my shiver DC or my stratos S8), that space can be used for the lower stanchions to slide through, and now you can essentially use this "extra space", and design more bushing overlap. That's why a lot of manufacturers initally designed inverted forks, and why motos have gone to inverted forks as well. The other aspect is that it's a lot cheaper for some companies like avalanche, stratos, foes, risse, mr dirt (basically the ones that have made them over the years) to make inverted forks because you don't have to invest in aluminum or magnesium casting equipment. The cast lowers that marzocchi, RS and fox use are prohibitively expensive compared to what you can do as a small manufacturer with a CNC machine and a lathe (simplifying here, but you get the point).

The inverted forks that are used in moto GP aren't really valid for our comparission either, they have very little travel, and very big stanchions. So pair 60mm or bigger stanchions with 4-5" of travel and super beefy crowns and such, and sure, it's going to be stiff, and maybe it does have lighter unsprung weight than a similer non-inverted setup. Go back to what I said about mountain bikes though, with casted lowers weighing around 3/4 of a pound, you're going to tell me that the weight saved will be significant? We're going to be looking at half a pound or less of difference between the setups when you consider the dropouts, axle, lower oil bath or internal fork parts. We're probably talking only a few hundred grams, if that. What's the entire mass of the unsprung weight? We're talking about saving significantly less than 10%, probably less than 5%, and closer to 2% realistically. Does that make ANY noticible difference? Also keep in mind that forks like the fox r40, boxxer, and others probably have the SAME or less amount of unsprung mass as the shiver did, due to less oil volume, closed-cell cartridges that use less oil, and so on.

About the only thing you can say with an inverted fork for mtb is that the lubrication is better, although not all companies have mastered oil seals, even in 2008 (so some of them shouldn't be making inverted forks IMO ). This "benefit" can be negated by having a good oil bath system in a right-side-up fork of course.

And what i mean by brake arches is that they help a lot to make our forks tortionally stiff (resist twisting). An inverted fork does not benefit from this. On motorbikes they obviously have no need for a brake arch in any situation, so you can't make the argument that "well motorbikes use inverted forks, so they must be stiff enough", because their non-inverted forks aren't going to be much different; they also lack a brake arch. With a mountain bike fork, the non-inverted design has a brake arch, and the inverted does not, this means that there's a lot more difference in stiffness when looking at mountian bike inverted vs. non-inverted and motorbike inverted vs. non-inverted.

The general idea here is that you can't make comparissions to motor bikes in terms of why we should use an inverted fork design. For mtb purposes, it's not practical. No tangible benefit to unsprung weight, manufacturers have gotten around the bushing overlap problem for 8" of travel by using bigger stanchions, and non-inverted forks are much stiffer in tortion and can be made that way with a lot less material than is required to do the same with an inverted design. Most people in the mtb world want lighter and stiffer, and with no tangible performance difference in unsprung mass, or even no difference in unsprung mass due to the explaination of damping carts and oil baths, people are going to go for what is stiffer and lighter and performs just as well. Hence why marzocchi came out with the 888. Pretty simple really. How many mainstream companies are making inverted forks right now? Why? Because they are not practical for mtbs at this point.

 

[blackspire]

Bushing overlap is the amount of stanchion that is "in" the fork bushing when it is resting and not being compressed. For the longest time marzochi tried to keep about 4" of overlap with all of their forks, I'm talking mostly about their single crown forks, but they did that with some of the double crowns as well.

So if you have an 8" non-inverted fork, the space between the upper and lower crowns is mostly hollow, maybe containing a spring, but usually just contains a spacer that extends down to where the spring starts. In other words this area serves a structural purpose for the dual-crown setup, but other than that it's not serving any other purpose. The bushing overlap is obviously within the lowers, and due to a finite amount of space, it can't be very large.

If you have an 8" inverted fork (like my shiver DC or my stratos S8), that space can be used for the lower stanchions to slide through, and now you can essentially use this "extra space", and design more bushing overlap. That's why a lot of manufacturers initally designed inverted forks, and why motos have gone to inverted forks as well. The other aspect is that it's a lot cheaper for some companies like avalanche, stratos, foes, risse, mr dirt (basically the ones that have made them over the years) to make inverted forks because you don't have to invest in aluminum or magnesium casting equipment. The cast lowers that marzocchi, RS and fox use are prohibitively expensive compared to what you can do as a small manufacturer with a CNC machine and a lathe (simplifying here, but you get the point).

Yes, but as you say the bushing overlap isn't really a problem. Thus my earlier statement that the main reason for designing an inverted fork is due to unsprung weight. While bushing overlap may have been a problem in the past it no longer is a important reason to design an inverted fork.

Regarding costs. Yes casting is expensive at the beginning and that might be a reason why companies choose other designs. And other ways of manufacturing are not necessarily worse, it might be for some applications though. But while casting might be expensive it's unlikely a major factor. Take Öhlins for example, they design some of the best suspension systems in the world. Money isn't really a problem there and their finish on the products they produce are world class and they still choose inverted.

The inverted forks that are used in moto GP aren't really valid for our comparission either, they have very little travel, and very big stanchions. So pair 60mm or bigger stanchions with 4-5" of travel and super beefy crowns and such, and sure, it's going to be stiff, and maybe it does have lighter unsprung weight than a similer non-inverted setup. Go back to what I said about mountain bikes though, with casted lowers weighing around 3/4 of a pound, you're going to tell me that the weight saved will be significant? We're going to be looking at half a pound or less of difference between the setups when you consider the dropouts, axle, lower oil bath or internal fork parts. We're probably talking only a few hundred grams, if that. What's the entire mass of the unsprung weight? We're talking about saving significantly less than 10%, probably less than 5%, and closer to 2% realistically. Does that make ANY noticible difference? Also keep in mind that forks like the fox r40, boxxer, and others probably have the SAME or less amount of unsprung mass as the shiver did, due to less oil volume, closed-cell cartridges that use less oil, and so on.

I'm not telling you that weight saved will be significant. I'm saying unsprung weight is the main reason to design inverted forks today. It's possible that the available solutions today are not better than a normal fork, but I'm pretty sure if a company like Öhlins would design an inverted front fork for MTB it would work damn well. I don't think 2% is all you can gain by changing to inverted. It's a shame Showas fork only was on the Honda RN01. Showa is a company that should be able to create an inverted fork for MTB that can perform very well.

About the only thing you can say with an inverted fork for mtb is that the lubrication is better, although not all companies have mastered oil seals, even in 2008 (so some of them shouldn't be making inverted forks IMO ). This "benefit" can be negated by having a good oil bath system in a right-side-up fork of course.

I bet it's more like they are too cheap to buy good oil seals if they can't get to seal properly. If you go to a company like SKF they have loads of seals for every axle diameter needed and you can just pick one of their expensive ones and it should perform well enough.

And what i mean by brake arches is that they help a lot to make our forks tortionally stiff (resist twisting). An inverted fork does not benefit from this. On motorbikes they obviously have no need for a brake arch in any situation, so you can't make the argument that "well motorbikes use inverted forks, so they must be stiff enough", because their non-inverted forks aren't going to be much different; they also lack a brake arch. With a mountain bike fork, the non-inverted design has a brake arch, and the inverted does not, this means that there's a lot more difference in stiffness when looking at mountian bike inverted vs. non-inverted and motorbike inverted vs. non-inverted.

I don't understand, where is this brake arch part? Is it the part that keeps the lower stanchions together? If that is the case yes it helps against shear stress. And that is one of the main problems for inverted forks. I don't understand why this wouldn't be a problem in motorbikes. It's the same reason why double crown forks are used, well maybe not exactly the same those are more used for tensile stress, but they are both there to reduce stress. And without a double crown fork it just says snap on almost all mx-bikes.

How many mainstream companies are making inverted forks right now? Why? Because they are not practical for mtbs at this point.

Or economical?


Also I got a question, on forks like the 888, where is the cartridge located is it attached to lower stanchions or is it attached to the inner leg at the top?

 

[How]

I've got extensive time with both the Shiver and the 888 RC, the 888 tracks better and has much better damping.

The Shiver is awesome, just more "primitive" damping, and the fork twists if you look at it wrong the integrated stem fixes this problem though.

Saying that, I don't have experience with the new 888 forks.

 

[cheetaprowlerDH]

^^ theres an answer i was looking for, thank you!

i have spent plenty of time on a factory 888RC and i loved it... it was an 05 or an 06, whatever it was it was FactoryCostcoDH's fork and it worked extremely well... he changed a bunch of crap internally and now i dont like the fork, but thats just my preference...
if the shiver tracks worse then i might just stay away... even that fork felt odd trying to pick and stay on a line...
my 888 held straight and true and it was wonderful, but it only used like 2 or 3 inches of travel beyond what i had it sagged at so it was pretty rough and didnt feel any better than my Monster...

is the ATA cartridge the internals for the whole left leg? if so i'll buy one and then take the fork to Drake and work on it with him...


maybe i could sell a kidney to buy a BOS and leave it on my bike until its as outdated as the Shiver:biggrin:

 

[ohio]

Jm_ the reason for UD forks is two-fold. Bushing overlap like you said and ALSO fore-aft stiffness. UD forks (for a given stanchion size and bushing overlap) are massively stiffer under braking. That's the primary reason street (and gp) motos use them, above unsprung weight and bushing overlap.

 

[Jm_]

Jm_ the reason for UD forks is two-fold. Bushing overlap like you said and ALSO fore-aft stiffness. UD forks (for a given stanchion size and bushing overlap) are massively stiffer under braking. That's the primary reason street (and gp) motos use them, above unsprung weight and bushing overlap.

Yep, that's along the same lines as I said fore-aft stiffness/strength when talking about big jumps/doubles on a motor bike, somewhat different application than dirt bikes, but similer reason.

 

[jamesdc]

I'm sure if you took a ton of pics of the fork torn aprt someone on this website would be able to help you get it back together. 888's arent that hard to work on. If your set on trying something different I'll swap you my x cartridge out of my rc2x if you buy a new PAR cartridge that way you'd have an rc2x instead. I dont know why everyone hates the shiver. I rode one for years and it never gave me any problems. They are only flexy when there is no weight on the bike, once the fork is sagged its as stiff as any other fork out there. As long as you change the oil a few times a year they work flawless. I actually like the inverted design better than conventioanl forks. If only someone would make an inverted fork with a 30mm hub, 200mm travel and rc2x internals, it would probably be the most popular fork out there.

 

[Kanye West]

The whole left leg internals (the ATA cartridge) can be ordered through Zoke and dropped right in to the fork. Top cap and bottom nut is all it takes. And if you're having issues accessing all the travel, just remove the PAR. For the '07 ATA chambers it does wonders. In '08 they made it slightly longer so it feels great with the PAR still in.

 

[cheetaprowlerDH]

i'll take pics of it today...
the fork is not disassembled because i cant get the footnut to come off and let the cartridge come out...

but i'll let the pics do the explaining...

about what is the cost for new internals?

 

[jamesdc]

about what is the cost for new internals?

new ata cartridge is around $240

 

[cheetaprowlerDH]

cheap? thats a whole used fork! and 3x as much money i have right now

i'm taking it to Drake, i talked to him on the phone today and he seems like an awesome guy! $25 for a full blown diagnosis? sh!t Performance charges $80 to bring a fork inside the shop!... not that they will actually fix a fork, but you get my point
and his diagnosis will probably fix my fork:biggrin: it will be so happy to be worked on by qualified hands

i bet everything in there can be fixed, but i am very, very far from qualified to do so...

 

[Kanye West]

I'm pretty sure it's not $240. Just calm down and call Zoke.

 

[cheetaprowlerDH]

Drake is the next best choice than straight from Zokie...

but i am not doing anything until i clear some stuff up with Sully about getting this thing fixed...

i'll save a Shiver purchase for some other bike:biggrin:

 

[jamesdc]

I'm pretty sure it's not $240. Just calm down and call Zoke.

Thats what zoke quoted me as retail. And thats without the footnut and adjustment knob, those cost even more.